Load persisted vector store by default (#753)

* load persisted vector stores by default, restoring previous behavior

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

packages/jupyter-ai/jupyter_ai/chat_handlers/learn.py

@@ -76,7 +76,10 @@ def _load(self):
                 return
 
             self.index = FAISS.load_local(
-                INDEX_SAVE_DIR, embeddings, index_name=self.index_name
+                INDEX_SAVE_DIR,
+                embeddings,
+                index_name=self.index_name,
+                allow_dangerous_deserialization=True,
             )
             self.load_metadata()
         except Exception as e: